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#1: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-29 22:12:35 by billycarrjr

I have a '99 Chevy Suburban 1500 4X4 with a 5.7L Vortec V8. It is
idling bad and you can smell strong gas fumes. Revs good but there is a
noticeable loss of power. The check engine light is on and we checked
it with an OBD II code reader.
P0300, multiple cylinder misfire intermittent code
P0430, catalytic converter fault? intermittent code
P0135, O2 heater sensor intermittent code
P0135, misfire #7 cylinder, constant code

Changed plugs with new AC Delco 41-932 platinums, same as factory
plugs. The rear 4 plugs showed rich with black deposits and #7 was wet
(fuel). The front 4 plugs were lean, gray, nearly white. Plug change
did nothing for the problem. New wires, cap and rotor and it still is
running bad. Pulled the #7 plug and it is wet again. If you run it at
2k rpms you can see the unburned fuel being blown out the exhaust. I
checked spark with an old plug and there is spark on #7. Also did a
quickie compression check on #7 cylinder and got 120 psi within 2
cranks with the throttle plate closed. Will do a complete correct
compression check later. #6 and 8 plugs are tough to get at with my old
body. Looked inside the throttle body and it is carboned up lightly
inside. I am going to run some decarbonizer thru the tank on advice
from the local parts guys.

Would you believe the local parts place can't get a manual for this
truck? They said they are a back order item. Guess I need to look
online and see what I can find cause that does not sound right. It
looks like a TBI system and there is an injector on either side of the
intake. Is it possible that one injector is feeding the front 4
cylinders and the other injector is feeding the rear 4? I have
searched user groups online for hours and it looks like a common enough
problem but it also looks like there is no clear cut solution. Seems
like folks are throwing parts at it and most never come back with any
positive results. What do y'all think? I'll rename my first born
male child after the person who gives me the fix. :-)

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#2: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-30 06:07:03 by master

hey bill! my name is mark. I have a very successful repair shop and
might be able to give you some advice. is the #7 cyl. plug wet with gas
or could it be antifreeze? That will determine the direction to go in.
If fuel which i suspect the problem should be fairly easy to diagnose
even though now a days its hard to diagnose anything without scanning
it first and looking at all the data. i have ran in to alot of the gm
cars with the plastic intake manifolds leaking around the rubber
gasket. the gasket sucks in causing the cylinder to run lean in turn
the computer will richen up the fuel mixture. but this usually is seen
on all cyls. check to see if there is any vaccum leaks on the #7 cyl
intake runner.(such as the brake booster vacuum, ect.) Also check to
see if you are getting enough spark. check this against other cyl. you
must be producing ahot enough spark to combust the fuel. also double
check your firing order (18436572) YOU could have fixed your problem
with your plug wires but got two crossed up and created a similar
problem. but most likely you either have a bad injector or a cracked
line going to the injector (there just made of a plastic line). the
best way to tell is to pull the upper intake off (seperating the
plastic upper from the lower aluminum manifold) which will expose the
fuel injectors and the lines. disconnect your coil so the vehicle wont
start, hook your fuel lines back up and plug your main injector
connector plug back in . have someone turn the key on engaging the fuel
pump and see if any of the fuel injector lines are leaking. if not you
can pull the injectors up out of the intake, leaving the fuel lines
connecting, have someone crank the engine over and see if #7 cyl
doesn't spray more fuel than the rest. if so replace injector. hope
this was some help. <a href="mailto:marklee8&#64;aol.com." target="_blank">marklee8&#64;aol.com.</a>

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#3: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-30 06:07:10 by master

hey bill! my name is mark. I have a very successful repair shop and
might be able to give you some advice. is the #7 cyl. plug wet with gas
or could it be antifreeze? That will determine the direction to go in.
If fuel which i suspect the problem should be fairly easy to diagnose
even though now a days its hard to diagnose anything without scanning
it first and looking at all the data. i have ran in to alot of the gm
cars with the plastic intake manifolds leaking around the rubber
gasket. the gasket sucks in causing the cylinder to run lean in turn
the computer will richen up the fuel mixture. but this usually is seen
on all cyls. check to see if there is any vaccum leaks on the #7 cyl
intake runner.(such as the brake booster vacuum, ect.) Also check to
see if you are getting enough spark. check this against other cyl. you
must be producing ahot enough spark to combust the fuel. also double
check your firing order (18436572) YOU could have fixed your problem
with your plug wires but got two crossed up and created a similar
problem. but most likely you either have a bad injector or a cracked
line going to the injector (there just made of a plastic line). the
best way to tell is to pull the upper intake off (seperating the
plastic upper from the lower aluminum manifold) which will expose the
fuel injectors and the lines. disconnect your coil so the vehicle wont
start, hook your fuel lines back up and plug your main injector
connector plug back in . have someone turn the key on engaging the fuel
pump and see if any of the fuel injector lines are leaking. if not you
can pull the injectors up out of the intake, leaving the fuel lines
connecting, have someone crank the engine over and see if #7 cyl
doesn't spray more fuel than the rest. if so replace injector. hope
this was some help. <a href="mailto:marklee8&#64;aol.com." target="_blank">marklee8&#64;aol.com.</a>

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#4: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-30 23:11:32 by billycarrjr

Hi Mark,
Thanks for your input. I am such a 70's car mechanic. I love
carburetors.
I double checked the firing order/wires and they are right. #7 plug
is wet with fuel not coolant. I drove it to town yesterday (5 miles) to
fill the tank and add the decarbonizer to the tank. It had no power and
when I added throttle it killed every insect within a square mile with
the cloud of vaporized fuel out the exhaust. Pulled over to let traffic
go by and it cleared up. Drove the 10 mile round trip and no more fuel
cloud but it is obviously missing, no backfiring just not hitting on
one or more cylinders. Today I swapped the front o2 sensors. No help. I
get constant P0307 fault code. I checked voltage and ground on the o2
sensor plugs and that is good. Noticed I have fuel dripping off the
left exhaust manifold where it bolts to the header pipe . Dripping off
the lower of the 3 studs. Tells me there is a lot of fuel being pumped
into the manifold.
I will try the injector check you outline. I bought a Chiltons that
covers '99 - '01 Chevy 1500 's and supposedly the Suburban. The engine
more closely resembles the V6 than the V8 in this book. It is a 350.
There is a large connector just to the rear of the horizontal throttle
body. It has 8 pairs of pins under it. Is this the injector pack? I
assume this is not a TBI. Each injector plugs into seperate runners of
the intake? I will start pulling the plastic intake cover tonight. Sure
sounds like I have a #7 injector pumping all the fuel it can into that
cylinder. I can live with an injector replacement.

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#5: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-31 00:08:41 by none

On 30 Dec 2004 14:11:32 -0800, &quot;Billy C (TX)&quot; &lt;<a href="mailto:billycarrjr&#64;gmail.com" target="_blank">billycarrjr&#64;gmail.com</a>&gt;
wrote:

&gt;Hi Mark,
&gt;Thanks for your input. I am such a 70's car mechanic. I love
&gt;carburetors.
&gt;I double checked the firing order/wires and they are right. #7 plug
&gt;is wet with fuel not coolant. I drove it to town yesterday (5 miles) to
&gt;fill the tank and add the decarbonizer to the tank. It had no power and
&gt;when I added throttle it killed every insect within a square mile with
&gt;the cloud of vaporized fuel out the exhaust. Pulled over to let traffic
&gt;go by and it cleared up. Drove the 10 mile round trip and no more fuel
&gt;cloud but it is obviously missing, no backfiring just not hitting on
&gt;one or more cylinders. Today I swapped the front o2 sensors. No help. I
&gt;get constant P0307 fault code. I checked voltage and ground on the o2
&gt;sensor plugs and that is good. Noticed I have fuel dripping off the
&gt;left exhaust manifold where it bolts to the header pipe . Dripping off
&gt;the lower of the 3 studs. Tells me there is a lot of fuel being pumped
&gt;into the manifold.
&gt;I will try the injector check you outline. I bought a Chiltons that
&gt;covers '99 - '01 Chevy 1500 's and supposedly the Suburban. The engine
&gt;more closely resembles the V6 than the V8 in this book. It is a 350.
&gt;There is a large connector just to the rear of the horizontal throttle
&gt;body. It has 8 pairs of pins under it. Is this the injector pack? I
&gt;assume this is not a TBI. Each injector plugs into seperate runners of
&gt;the intake? I will start pulling the plastic intake cover tonight. Sure
&gt;sounds like I have a #7 injector pumping all the fuel it can into that
&gt;cylinder. I can live with an injector replacement.

Sounds like you are on the right track suspecting a bad injector on
#7. Please post back and let us know how it comes out. You've got me
curisoity up on this one.

Steve B.

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#6: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-31 18:52:30 by billycarrjr

I got the plastic intake upper manifold off. Taking a break to let my
legs unkink. The rear half of the aluminum manifold is wet, the front
half is dry, all of it is sooty. Reconnected the fuel lines and
injector connector. Turn the key to on position and the pump runs but
no leaks that I can see. I am getting ready to pull the pop off
nozzles out and try cranking it and see what I see. I sure wanted to
see a leaking plastic line. Looks like if one was cracked it would
spray all over in the rear and go right down the runners into the
cylinder. I think I will try moving them around a bit with the fuel
system pressurized. I want to post a pic for everyone to see this but
apparently I can't do it on this board. If you want to see what it
looks like under that black plastic cover copy/paste this link to your
browser address bar and hit enter.
<a href="http://members.sparedollar.com/billyc/Suburban-engine-019-sm.jpg" target="_blank"> http://members.sparedollar.com/billyc/Suburban-engine-019-sm .jpg</a>

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#7: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-31 20:57:40 by billycarrjr

Good news/ bad news. Pulled all the popoff lines and pressurized the
system. #7 injector was spraying full tilt while none of the others
were. Yeehaa! Got a fix. Run up to O'Rellys and they got a new
BorgWarner injector for $60.00. Installed it. Repressurize the system
and it still sprays fuel nonstop. Damn! Pull the connector on the
injector pack and it stops spraying. Appears to me that I have a
signal telling it to stay open. What now guys? Thanks for the help.
Y'all pointed me in the right direction so far.

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#8: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-31 22:03:51 by billycarrjr

I checked voltages and resistance on the injector pack connector. Key
on, 11 1/2 VDC on all 8 injectors. Other pin open circuit/infinite
resistance on 7 injectors and the #7 injector has appx 560 ohms. Bingo!
Bad input signal. PCM is faulty? What do I do next?

Happy New Years to everyone out there. Drive sober, I'll be out there
on the road with you. Just not in a Suburban.

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#9: Re: 5.7L Vortec running way rich, poor idle

Posted on 2004-12-31 23:23:20 by none

On 31 Dec 2004 13:03:51 -0800, &quot;Billy C (TX)&quot; &lt;<a href="mailto:billycarrjr&#64;gmail.com" target="_blank">billycarrjr&#64;gmail.com</a>&gt;
wrote:

&gt;I checked voltages and resistance on the injector pack connector. Key
&gt;on, 11 1/2 VDC on all 8 injectors. Other pin open circuit/infinite
&gt;resistance on 7 injectors and the #7 injector has appx 560 ohms. Bingo!
&gt;Bad input signal. PCM is faulty? What do I do next?
&gt;
&gt;Happy New Years to everyone out there. Drive sober, I'll be out there
&gt;on the road with you. Just not in a Suburban.

I'm out of my league here but I would suspect a PCM issue or a wiring
issue on the way to the pcm. I would unplug the PCM and check the
resistance on that wire again and see if it changes. If it drops to 0
then I guess your off to the junk yard to find another pcm.

Steve B.

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#10: Re: 5.7L Vortec running way rich, poor idle

Posted on 2005-01-01 00:58:59 by Comboverfish

First, make sure that your injectors resistances' all read very close
to each other. Measure ohms across the two pins of each injector in
the fuel metering body.

If they are all very close, then check the wiring. Your #7 injector
has a Red / Black signal wire that controls it. It goes from the large
connector on the intake manifold to the engine computer (VCM) on the
left fender. You're lucky here because it's easy to do pin and wire
tests. The #7 injector wire is terminal #12 in &quot;Connector 2&quot; of the
VCM. I can't tell you which connector C2 is exactly, but there are 3
large connectors that are the same size and &quot;C2&quot; is one of those. If
you count over 12 pins from the edge of every connector you will most
likely only find one Red / Black wire that is 12 pins from one end.

With the injector and C2 plugs both disconnected, check resistance of
either Red / Black terminal to body ground. You may find a short there
that's keeping that injecter open. Also test the wire end to end for 0
resistance while you're there.

If there's no short to ground, look to see if the VCM is providing the
correct signal. If you could access a scope you could actively
backprobe the Red / Black wire with the engine running to get a voltage
waveform - which would be great. Second best would be a noid light
used in place of the injector while cranking to verify injector pulse
signal. Thirdly you could use a DVOM with pulse width measurment
capability to check for a reasonable injector on-time. Compare to the
other known good injector signals if in doubt.

A good wire and bad signal means its time for a new VCM. I think your
new VCM will need to be programmed either by a GM Dealer or a good
independent shop with the required (expensive) equipment.
Good luck,
Toyota MDT in MO

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#11: Re: 5.7L Vortec running way rich, poor idle

Posted on 2005-01-02 03:52:38 by billycarrjr

Injectors all read the same, appx 10.5 ohms. Measured the #7 wire to
chassis gnd and it reads short when connected at the PCM and open with
the White connector unplugged from The PCM. No fancy test equipment
available to me so I can't look at injector signals.

Disconnected neg terminal of battery. Checked ground signal wire on the
connector for the #7 injector, appx 300 ohms to chassis ground.
Unplugged the connector on the PCM labeled white. It is one of 4,
white, black, red, blue. It is the top forward one. Ground went away.
Plug it back in and ground comes back. I got a line on a cheap used PCM
said to be good. Big question is - the Serv # on my truck and the Serv
# on the PCM from the same make/model salvage truck are the same. Does
this mean I can plug it in and drive? No need for a reprogram by the
dealer?

I did measure the wire end to end for continuity and got an open. I am
certain I was on the pins and the DVM is good and setup right. I was on
the red/black wire on the PCM White plug and on the ground pin on the
#7
injector plug. I have no idea why I am not getting a short there.

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#12: Re: 5.7L Vortec running way rich, poor idle

Posted on 2005-01-02 07:08:13 by Comboverfish

In the incredible, this one's for the books, wacko possibility that the
Red / Black wire is burned and intermittantly chaffed against another
exposed ground source inside the harnass -- this would ground your
injector and show no continuity on the end to end wire test.

Of course that scenario is hard to believe. I really think you need to
make sure with the correct wiring diagram and connector picture in
front of you that you are testing the correct circuit. I honestly
think that that wire is in good shape because its transmitting ground
to the injector when atttached. You probably have a partially grounded
injector output inside the VCM. Atleast try to check a couple of the
other injector circuits with the very same tests to get something to
compare to. After doing it a couple of times you can trust your
diagnosis, even if it points to a really wierd problem.
Good luck,
Toyota MDT in MO

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#13: Re: 5.7L Vortec running way rich, poor idle

Posted on 2005-01-03 01:41:42 by billycarrjr

and sure enough I was on the wrong connector of the PCM . The wire is
good and checked it at the pin on the PCNM to ground and it reads appx
300 ohms to gnd and the injector pin next to it reads open as it
should, Bad PCM. Just won a PCM from a '99 Suburban with the same Serv
# for $35.00 shipped to my door. :-) He says it is good. We will
install and if it starts run it down to the dealer and get it flashed
to be sure we are right. I will post the results when it's all over.

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#14: Re: 5.7L Vortec running way rich, poor idle

Posted on 2005-01-03 05:01:37 by Comboverfish

Sweet! Please do follow up. Hope it works out perfectly.
Toyota MDT in MO

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#15: Re: 5.7L Vortec running way rich, poor idle

Posted on 2005-01-07 16:27:37 by Bob

&quot;Billy C (TX)&quot; &lt;<a href="mailto:billycarrjr&#64;gmail.com" target="_blank">billycarrjr&#64;gmail.com</a>&gt; wrote in message
news:<a href="mailto:1104444692.717145.61330&#64;c13g2000cwb.googlegroups.com..." target="_blank">1104444692.717145.61330&#64;c13g2000cwb.googlegroups.com...</a>
&gt; Hi Mark,
&gt; Thanks for your input. I am such a 70's car mechanic. I love
&gt; carburetors.
&gt; I double checked the firing order/wires and they are right. #7 plug
&gt; is wet with fuel not coolant. I drove it to town yesterday (5 miles) to
&gt; fill the tank and add the decarbonizer to the tank. It had no power and
&gt; when I added throttle it killed every insect within a square mile with
&gt; the cloud of vaporized fuel out the exhaust. Pulled over to let traffic
&gt; go by and it cleared up. Drove the 10 mile round trip and no more fuel
&gt; cloud but it is obviously missing, no backfiring just not hitting on
&gt; one or more cylinders. Today I swapped the front o2 sensors. No help. I
&gt; get constant P0307 fault code. I checked voltage and ground on the o2
&gt; sensor plugs and that is good. Noticed I have fuel dripping off the
&gt; left exhaust manifold where it bolts to the header pipe . Dripping off
&gt; the lower of the 3 studs. Tells me there is a lot of fuel being pumped
&gt; into the manifold.
&gt; I will try the injector check you outline. I bought a Chiltons that
&gt; covers '99 - '01 Chevy 1500 's and supposedly the Suburban. The engine
&gt; more closely resembles the V6 than the V8 in this book. It is a 350.
&gt; There is a large connector just to the rear of the horizontal throttle
&gt; body. It has 8 pairs of pins under it. Is this the injector pack? I
&gt; assume this is not a TBI. Each injector plugs into seperate runners of
&gt; the intake? I will start pulling the plastic intake cover tonight. Sure
&gt; sounds like I have a #7 injector pumping all the fuel it can into that
&gt; cylinder. I can live with an injector replacement.
&gt;
Billy, I didn't see a post with the &quot;final answer&quot;. Just curious what you
found that fixed it.
Thanks,
bb

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#16: Re: 5.7L Vortec running way rich, poor idle

Posted on 2005-01-08 18:43:03 by billycarrjr

The problem was with the PCM. $35.12 with shipping from ebay and $73.45
to flash program it at the dealer. Got real lucky on the ebay find but
always worth a look before you go to the salvage yard or dealer. It
runs great now! Thanks guys. Saved me a huge repair bill at the
dealership.

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